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SE Martins - 28th to 32nd Ave

Introduction

The Traffic Calming Program (TCP) undertook a streamlined speed bump
project in the Summer of 1997 to address traffic problems identified by
residents along SE Martins from 28th to 32nd Avenue.

The goal of the project was to enhance street safety and livability by
reducing the 85th percentile speed of vehicles using SE Martins closer to the
legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only
devices considered for streets like SE Martins, which are classified as Local
Service Streets, are not transit or primary fire response routes and have
vehicle volumes between 400 and 1700 vehicles per day. Speed bumps have proven
to be effective tools to reduce vehicle speed without affecting access. It is
not an intended goal to reduce traffic volume on low-volume Local Service
Streets.

SE Martins serves a single family residence neighborhood. SE
28th Avenue, to the west, is a Neighborhood Collector street. SE 32nd
Avenue, at SE Martins's east end, is a Local Service street. SE Martins has side
walks and curbs. Additionally, there are horizontal curves and a slight grade
toward 28th Avenue. A large portion of the daily traffic on SE
Martins is believed to be cut-through traffic avoiding the intersection of
28th and Woodstock. This movement is facilitated by an all-way stop
at 32nd and Woodstock, a Neighborhood Collector adjacent to Reed
College.

Open House

Residents along SE Martins were invited to an open house October
2, 1997 to review and comment on the proposed speed bump installation. Sixteen
people attended the open house. Most of those who attended expressed approval
for the proposed project. There was concern expressed about the appearance of
the bumps as well as fears the bumps would cause a large change in traffic
patterns on adjacent streets. A petition was available at the open house for
residents along SE Martins to sign and was circulated after the open house by a
local resident. Petition results were as follows:

Category

Number

Percent of
Total

Yes

13

76.5%

No

0

0%

No Signature

4

23.5%

Total

17

100%

Vacant

0

Performance

Two 14-foot speed bumps, at 417 foot spacing, were constructed along the
0.14 mile length of SE Martins, 28th to 32nd Avenue, on April 5th and
17th, 1998 by the Bureau of Maintenance. One of the bumps was a test
installation of a rubber speed bump.

Vehicle Speeds

As the graph (over) shows, vehicle speeds, previously spread between 23 and
31 mph, have been shifted into the range of 20 to 22 mph. The average 85th
percentile vehicle speed before the project was 32 mph. Since bump construction
the average 85th percentile speed is 24.6 mph and ranges from a low of 18 mph
(near the bumps) to a high of 28 mph in the 25 mph zone. Before installation of
the speed bumps 53% of drivers exceeded the posted speed limit of 25 mph and 6%
exceeded the limit by 10 mph or more. Since bump construction 13% of drivers
exceed the posted speed limit and 0.3% exceed the limit by 10 mph or more.